Radio control system



19410" E. F. M DONALD, JR

RADIO CONTROL SYSTEM 1940 3 Sheets-Sheet 1 Filed July 25 u PUwQ O 194 E. F. M DONALD. JR

RADIO CONTROL SYSTEM Filed July 25, 1940 3 Sheet's-Sheet 2 011- 1, 9 E. F. M DONALD. JR

I RADIO CONTROL SYSTEN Filed July 25, 1940 3 Sheets-Sheet 3 Patented a. 1, 1940 UNITED, I'S'T'ATVES PATENT OFFICE namo CONTROL SYSTEM EugeneF. McDonald, In, Chicago, Ill.

Application July 25, 1940, Serial No; 347,516

15 Claims.

wherever it is desired to control a radio receiver.

The conventional hand tuning or actuation by hand of station selectors with conventional automobile radio receiver installations constitutes a serious hazard as the drivers'attention is distracted and serious accidents have frequently resulted. Furthermore, it is many times important to mute the radio receiver for short periods of time in order to be able to listen for warning bells at railroad crossings or for the sounds of approaching vehicles or trains.

20 In accordance with the present invention, muting of the radio receiver for controlled periods of time as well as the selection of the desired signal to be received can be accomplished through a single member actuated, for example, by foot control with a special type of switch mounted on the floorboard of an automobile. This enables the control operations of the radio receiver, which ordinarily require close attention by the driver, to be carried out without requiring the driver to look at the radio set or remove either hand from the steering wheel.

\ In addition to the safety features above discussed the driver can easily mute the radio receiving set in order to engage in conversation with passengers and furthermore, a plurality of control devices can be employed so that control of the radio set may be accomplished from the rear seat or the passenger's side of the front seat, if desired.

It is, therefore, an object of the present invention to provide an improved control system for a radio receiving set.

Another object of the invention is to provide an improved safety control system for an automobile radio receiving set.

Another object of the invention is to provide an improved device for muting a radio receiver or selecting a desired signal or performing both of these functions simultaneously.

A further object of the invention is to provide a system for controlling changing the transmitting station being received and muting of the radio set from a remote point by a single actuating member.

Other objects and advantages of the invention will appear in the following description of preferred embodiments thereof disclosed in the attached drawings of which:

Figure 1 is a schematic diagram of a. radio set and control mechanism embodying the present invention.

Figure 2 is a vertical section through a switch mechanism which may be employed in the present invention.

Figure 3 is a horizontal section taken on the line 3-3 of Figure 2.

Figure 4 is a fragmentary vertical section taken on the line 4-4 of Figure 3.

Figure 5 is a vertical section through a modified form of mechanism adapted to be employed in the present invention.

Figure 6 is a fragmentary vertical section of the device of Figure 5 taken at right angles thereto.

Figure '7 is a horizontal section taken on the line 1-1 of Figure 5.

Figure 8 is a plan view of a releasing ring of the switch of Figure 5.

Figure 9 is an elevation of the locking sleeve of the switch of Figure 5.

Figure 10 is an elevation of the sleeve of Figure 9 taken at right-angles thereto.

Referring to Figure 1, l5 indicates diagrammatically the various sections of a conventional radio receiving set. All of the circuits of the set are not shown but the circuits necessary for an understandng of the present invention are shown exteriorly of the diagrammatic representation l5 of the set. Thus, the antenna l5 and an antenna coupling and radio frequency tuning circuit I1 is shown connected to the radio frequency stage of the set IS; an oscillator frequency control circuit I8 is shown connected to the oscillator and mixer section of the set, and an output circuit I 9 is shown connected to the audio frequency section of the set. The antenna coupling and radio frequency tuning circuit I! may include an antenna choke 20, an antenna coupling condenser 2i, and a radio frequency tuning coil 22. One terminal of the coil 22 may be grounded at 23 and its other terminal connected to a movable contact 24 of a station selector switch 25. The stationary contacts A, B, C and D of the switch 25 may each be connected to one terminal of separate presettable condensers 26 which have their other terminal connected to ground at 21. The stationary contact M of the switch 25 may be connected to one terminal of a variable condenser 28 forming one condenser of a two condenser gang providing forv manual or dial tuning of the set. The other terminal of the condenser 28 may be connected to ground at 29. A trimmer condenser 30 may be connected across the condenser 29. It is apparent that rotation of the switch will selectively place a desired condenser 26 or condensers 28 and 30 across the tuning coil 22 to provide parallel radio frequency tuned circuits.

The oscillator frequency control circuit [8 may include a coil 3| which may have one terminal connected through a condenser 32 to the plate or anode grid of an oscillator tube (not shown) and its other terminal connected to ground at 33. Such an arrangement can be employed with a shunt fed oscillator, although obviously the invention can be adapted to other types of oscillator circuits. The movable contact 34 of a second selector switch 35 may be connected to the grid of the oscillator tube (not shown) through a condenser 35. Each of the stationary contacts A, B, C and D of the switch 35 may be connected to one terminal of separate presettable inductances 36 having their other terminals connected to ground at 3'1. The inductances 36 may be of variable permeability type in which an adjustable iron core is employed to preset the desired value of inductance. The contact M of the switch 35 may be connected to one terminal of a variable condenser 38, forming the other condenser of the two condenser gang, for manual tuning. The other terminal of the condenser 38 may also be connected to ground at 39 and a trimmer condenser 40 may be connected across the condenser 38.

The movable contact 4! of a third selector switch 42 may be connected to the movable contact 34 of the switch 35. Stationary contacts A, B, C, and D of the switch 42 may be connected to one terminal of a fixed condenser 43 having its other terminal connected to ground at 44. The contacts A, B, C, and D of the switch 42 may a1- so be connected to one terminal of a coil 45 coupled to the oscillator coil 3! having its other terminal connected to ground at 46. The stationary contact M of the switch 42 may be connected to one terminal of a coil 41 coupled to the coil 3| and having its other terminal connected to ground at 48 through a tracking condenser 49. It will be apparent that simultaneous rotation of the switches 35 and 42 will selectively connect the adjustable inductances 36 across the coil 45 and also across the condenser 43. The variable inductances 36, coil 45 and condenser 43 provide parallel grid circuit tuning circuits and adjusting the appropriate variable inductance 38 will provide the proper oscillator frequency for any desired station. When the switches 35 and 42 reach the contact M the variable inductances 36, condenser 43 and coil 45 are disconnected from the circuit and the manual tuning condenser 38 and the coil 4'! are connected in parallel to form a parallel grid circuit tuning circuit for the oscillator frequency under control of the condenser 38. It is also apparent that an adjustable condenser 26 in combination with a corresponding adjustable inductance 35 comprises a means for presetting the receiver for any desired station and that a plurality of such presettable means are provided. The tuning circuits described above are given merely by way of example as many other types of tuning circuits involve adjustable condensers in both the antenna coupling circuit and the oscillator circuit as well as in other radio frequency circuits or involving variable inductances in any of these circu t 5 well as variable inductances for manual tuning may be employed.

In accordance with the present invention, all of the switches 25, 35 and 42 may have their movable contacts mechanically connected by means of a shaft 50 shown in dotted line. The shaft may be provided with a ratchet 51 for step by step rotation of the shaft 59 by means of a reciprocable solenoid core 52 provided with a pawl 53 pivoted thereto, the core and pawl being returned to normal positionby a spring 54. Energization of the solenoid coil 55 moves the core 52 and pawl 53 downwardly in Fig. 1 to rotate switches 25, 35 and 42, one step for each actuation of the solenoid. By employing another switch 56 having a movable contact 51 rotated by the shaft 50, one position of the shaft 50 may be utilized to disconnect the receiver from its source of power, thus the contacts 0 of the switches 25, 35 and 42 may be left unconnected and a notch 58 in the movable contact of the switch 56 arranged to break contact with the stationary contact 59 thereof when the movable contacts of the other switches are in engagement with the contacts 0 of these switches.

In accordance with conventional practice, the storage battery 60 of an automobile having one of its terminals connected to ground at El may be employed to energize the circuits of set l5.

Thus, the battery 60 may have its other terminal connected to the movable contact 51 of the switch 56 through an ignition switch El and a manually operated control switch 62 and stationary contact 59 of the switch 56 may be connected to the power supply of the radio set.

The solenoid coil 55 may likewise have one of its terminals connected to the battery 60 through the switches 6i and 62. The other terminal of the solenoid coil 55 may be connected through a thermal cutout 63 and conductor 63 to a stationary contact 64 of a foot actuated control switch 65 mounted upon the floorboard B5 of the automobile and having a movable member 66 connected to ground at B1. The switch 55 may mave a muting contact 88 connected through a conductor 68 to one terminal of the voice coil 10 of the output circuit IQ of the radio set. The other terminal of the voice coil 10 may be connected to ground at 1 I. The muting contact 69 of the switch 65 may be positioned to be engaged by the movable member 66 prior to engagement between the movable member 65 and the contact 64. Thus, initial movement of the member 58 of the switch 65 short circuits the voice coil 10 to mute the radio set. The muting system shown is extremely efficient and perhaps the simplest, but it is apparent that a switch may be employed to effect operation of any other desired means of muting a radio set.

. As previously described, the most desirable position for the switch 65 is upon the fioorboard in the drivers compartment of the car so as to enable actuation of the switch by the foot of the operator. However, the switch may be positioned in any of the passenger compartments of prevented by employing the thermal cutout 83 in series with the coil 55. This thermal cutout may include a heater resistor I3 and a snap action bimetallic element I4. Current flowing through the resistor I3 heats the bi-metallic element to cause it to snap away from the stationary contact I5. This breaks the circuit through the resistor I3 and solenoid coil 55 until the bi-metallic element has cooled sufiiciently to again snap back into engagement with contact I5. Each time the contact between the bi-metallic element I4 and I5 is broken and reestablished the solenoid coil 55 is energized to rotate the switches operated thereby, thus apprising the driver of the vehicle that he is holding the switch 65 in its fully actuated position. Also the time of current flow through the solenoid coil 55 is decreased. The thermal cutout 63 may be adjusted to give relatively slow action and used purely as a safety device or it may be adjusted to provide rapid action whereby holding the switch 55 in its fully actuated position will rapidly step the switches 25, 26' and 42 until the desired station is reached, at which time the switch 65 may be released.

A preferred type of switch 65 is shown more in detail in Figures 2 to 4. This switch causes muting of the ratio set upon partial depression and changing of the station being received upon full depression and may comprise a casing 15 with the movable member 56 forming a cover for the casing I5. The casing 15 and movable member 66 may have lateral extensions 1! and I8 respectively, loosely secured together at 19 by a rivet or the like so that the movable member 66 may pivot about the rivet I9 when depressed by the foot of an operator of a vehicle. The movable member 66 may be held in its uppermost position by means of a spring engaging an annular spring retainer 8I supported by the casing 15. The casing 15 may have an upwardly extending annular portion 8| slotted at 82 to receive projections 83 carried by a plate 84 of insulating material. The plate 84 is'held in its uppermost position by means of a spring 85 bearing against a shoulder 86 on the interior of a casing I5. The plate 84 may be held within the casing I5 by means of lugs 81 forming part of the annular member 8I of the casing I5, the lugs being bent inwardly over the plate 84.

The plate 84 is provided with a central aperture 88 which is surrounded by the muting contact 58 comprising an annular metal member secured to the plate 84. The muting contact 68 is connected to the conductor 68' extending from the casing I5 between themextensions 11 and I8. The movable member 66 may be provided with a downwardly extending portion 9I having a contact member 92 secured thereto and with a downwardly projecting annular portion 93 for contacting the muting contact 68 carried by the plate 84. The solenoid operating contact 64 connected to the conductor 63, also extending from the casing, is insulated from the casing I5 as shown in Figure 2.

It will be apparent that partial depression of the movable member 65 against the force of the spring 80 will cause the annular member 93 of the movable member to first come in contact with the muting contact 58 of the plate 84. Themovable member 55 is connected to ground as shown in Figure land this contact completes a circuit from the conductor 68' to ground thus muting the radio set as shown in Fig. 1. Further, depression of the movable member 65 moves the plate 84 against the force of the spring 85 until the contact 92 of the movable member engages the contact 54 to complete a circuit from conductor 53 to ground, which as shown in Fig. 1 completes the circuit through the solenoid coil 55. The spring 80 is preferably a light spring requiring only a slight amount of pressure to actuate the movable member into contact with the muting contact 58. The spring 85 is preferably much stronger than the spring 80 so that considerably more pressure is necessary to force the contact 92 into engagement with the solenoid operating contact 64. The operator of the switch can thus readily'actuate the switch to mute the radio set without changing stations or alternatively can operate the switch to change stations. The radio set remains muted during station changing and by only partially releasing the switch, not far enough to break the muting circuit, the operator may cycle the station selecting apparatus through several stations while holding the radio set muted.

An alternative form of switch is disclosed in Figs. 5 to 10. With this type of swich partial actuation of the switch will mute the radio set and retain the set muted after the switch has been released. actuation of the switch will release the muting contact. Such full actuation will also change stations. Also, a full actuation of the switch at any time will change stations and release the muting of the radio set when the switch is released irrespective of the condition of the switch at the beginning of the full actuation.

The switch of Figures 5 to 10 may include a casing 95 provided with a movable member 96 telescoping therewith and held in its uppermost position by a spring 91. The movable member 95 is held in position upon the casing 95 by means of screws 98 extending into slots 99 in the casing to enable'downward movement of the member I02 shown more clearly in Figures 9 and 10 may surround the circular member I00 and be urged upwardly by means of a spring I03. The sleeve may be provided with a plurality of spring fingers I04 formed from the metal of the sleeve. In the uppermost position of the sleeve the spring fingers I04 have their upper portions I04 compressed within slots I05 in an aperture in a plate of insulating material I06. The plate I06 is slidably mounted in the casing 95 and held in its uppermost position by a spring I01. Initial downward movement of the movable member 96 drives the sleeve I02 downwardly to an intermediate position where the spring fingers I04 spring outwardly and latch under the insulating plate I06. The initial downward movement of the sleeve brings the lower portion I08 thereof into contact with spring muting contacts I09 carried on a metal sleeve IIO insulated from the casing 95. The sleeve II 0 is connected to the conductor 68 so that a circuit is completed from the movable member 96, which is grounded, to the conductor 58. Upward movement of the movable member 96 leaves the sleeve I02 in its intermediate position by compressing the spring I03 since the sleeve is latched in this position by its spring fingers I04. This leaves the radio set in muted condition.

As shown in Figure 6 which is a partial vertical section at right angles in view of Figure 5, a member I I0 is secured between the movable mem- A subsequent, partial or full I ber 98 and the circular member I00 and provided with spring fingers I I I which are resiliently urged inwardly toward the sleeve I02. In the normal or completely off position of the switch shown in Figures 5 and 6 the spring fingers III are held outwardly in the position shown in Figure 6 by lugs II2 struck outwardly from the sleeve I02. When the sleeve I02 has been latched in its intermediate position by the spring fingers I04 and the movable member 96 allowed to return to its upper position, the spring fingers II I move inwardly above the lugs II2. Subsequent partial depression of the movable member 96 moves the sleeve I02 to a lowermost position still keeping the radio set muted. A releasing ring [I3 held centered by lugs I I4 extending upwardly through apertures in the plate I06 earns the spring fingers I04 inwardly during this further movement of the sleeve and holds the same in their inward position. The spring fingers III engaged above the lugs II2 on the sleeve are at the same time cammed outwardly by cam members H5 carried by the insulating plate I06 so as to clear the lugs H2, the lugs II2 being positioned between the small cams on the cam members. This releases the sleeve I02 which is then forced upwardly by the spring I03 into its intermediate position with the spring fingers I04 thereof carrying the releasing ring H3. If the movable member 96 is then released, this motion of the sleeve continues until the upper portions I04 01' the spring fingers I04 are positioned within the slots I05 in the plate I05 and the sleeve is in its uppermost position so that the muting circuit is broken. During the latter part of this upward movement the releasing ring I I3 is stripped from the upper portions I04 of the spring fingers I04 by the plate I06 so as to condition the fingers to be again latched under the plate I06. Thus, a second partial actuation and release of the movable member allows the sleeve I02 to return to its uppermost position breaking the contact between the lower portion I08 of the sleeve I 02 and muting contacts I09 to remove the muting action on the radio set. I

If the movable member 96 is completely actuated at any time depending portions IIS (Fig. 5) upon a member I I! also secured between the circular member I00 and the movable member 96 engage the plate I06 after initial movement of ,the movable member and depress the plate against the action of the spring I01. Complete actuation of the movable member 96 brings the contact member IOI carried thereby into contact with a stationary contact II8 insulated from the casing and connected to the conductor 63'. Such complete depression of the movable member 98 will always move the sleeve I02 to its lowermost position so that upper portion I04 of the spring fingers I04 will always be engaged within the releasing ring H3. The sleeve I02, therefore, always returns to its uppermost position upon release of the movable member 96 after a complete actuation thereof. Nevertheless, the lower portion I08 of the sleeve I02 will be kept in contact with the contact members I09 during initial upward movement of the movable member 86 after complete actuation thereof so that the contact between contacts WI and H8 may be repeatedly broken and reestablished without releasing the muting action. The solenoid coil 55 of Fig. 1 may thereby be repeatedly energized to step the switches through a plurality of steps while keeping the radio set muted.

It will, thus, be seen that partial actuation of either the switch of Fig. 2 or the switch of Fig. 5 will first mute the radio set. Release of the switch of Fig. 2 after partial actuation will remove the muting action on the radio set whereas release of the switch of Fig. 5 will cause the radio set to remain muted until the switch has been again actuated. Both switches can be completely actuated to cause a station change. With both switches the radio set remains muted during the station changing operation and partial release of the switch followed by another actuation of the switch will cause a second station change while the radio set remains muted and this operation may be repeated as often as desirable. A complete actuation of the switches of either Fig. 2 or Fig. 5 and release of the switch will always remove the muting action from the radio set irrespective of whether the set was muted prior to such action.

Thermal cutout 63 of Fig. 1 may be employed with either type of switch as a safety or overload device for preventing excessive discharge of the battery 60 or burning out of the solenoid coil 55, by adjusting the same for slow relatively operation. It may also be employed both as a safety device and to secure a plurality of relatively rapid operations of the station changing mechanism by single depression of the main actuating switch. The former operation is preferred as an operator familiar with the station setting of a particular radio set may select any station with respect to the station previously being received by counting the number of complete actuations of the switch.

A plurality of switches such as those shown in Figs. 2 and 5, may be employed in parallel so that the receiver may be controlled from more than one point. In most installations the switch 56 for shutting off the radio set in one position will ordinarily be omitted and a lesser number of switch positions employed for a given number of stations. In any event, the system of the present invention enables station changing and muting of the radio set by a single foot operated control device without the operator having to look at the set or dial or remove his hand from the automobile controls. The system of the present invention is particularly applicable to the control of automobile radio sets and has been described in detail with respect to operation from low voltage batteries. However, other types of'radio sets such as sets operated from alternating current or higher voltage direct current may be operated from a remote point in accordance with the principles of the present invention. The invention has been illustrated in connection with an "electrical type of automatic tuning wherein individual presettable condensers or inductances are employed, but is also applicable to other types of automatic tuning arrangements.

While I have disclosed the preferred embodiments of my invention it is understood that the same is-not limited to the details disclosed but may be varied within the scope of the following claims.

I claim:

1. An automobile radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitpedal positioned on the floor board of said automoblleto be actuated by the driver of said automobile.

2. An automobile receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, selecting means for selecting a desired one of said presettable means, and means for operating said selecting means to select any one of said presettable means including a solenoid for actuating said selecting means and a foot switch positioned on the floor board of said automobile to be actuated by the driver of said automobile for controlling the operation of said solenoid.

3. An automobile radio receiving :system comprising a receiving set having a plurality of presettable means for presetting said set to receive asignal from any one of a plurality of transmitting stations, selecting means for selecting a desired one of said presettable means, muting means for said set, and control means for said selecting means and said muting means including a foot pedal capable of partial or full actuation and positioned at the floor board of said automobile to be actuated by the driver of said automobile, means for operating said muting means upon partial actuation of said pedal and means for operating said selecting means upon full actuation of said pedal.

4. An automobile radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, selecting means for selecting a desired one of said presettable means, muting means for said set, and control means for said selecting means and said muting means including a foot pedal capable of partial or full actuation and positioned at the floor board of said automobile to be actuated by the driver of said automobile, means for operating said muting means upon partial actuation of said pedal and means for operating both said muting means and said selecting means upon full actuation of said pedal.

5. A radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, muting means for muting said set, a stepby-step selecting means for selecting a desired one of said presettable means, and controlling means for said muting means and said selecting means including a movable member capable of partial or full actuation, and means for operating said muting means to mute said set upon partial actuation of said member and for both stepping said selecting means to select any one of said presettable means and operating said muting means upon full actuation of said member.

6. A radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, muting means for muting said set, a stepby-step selecting means for selecting a desired one of said presettable means, and controlling means for said muting means and said selecting means including a solenoid for stepping said selecting means, a movable member capable of partial or full actuation, means for operating said muting means to mute said set upon partial actuation of said member, and means for operating both said muting means to mute said set and said solenoid to step said selecting means upon full actuation of said member.

"I. In a system for controlling a radio receiver, a plurality of presettable means for presetting said receiver to selectively receive a signal from any one of a plurality of transmitting stations, step-by-step selecting means for selecting a desired one of said presettable means, muting means for said receiver, an actuatable member having at least two controlling positions, and means for operating said muting means without operating said selecting means at one controlling position of said member and for operating said muting means and stepping said selecting means at another controlling position of said member.

8. In a system for controlling a radio receiver, a plurality of presettable means for presetting said receiver to selectively receive a signal from any one of a plurality of transmitting stations, step-by-step selecting means for selecting a desired one of said presettable means, muting means for said receiver, a movable member having a normal position and actuatable through a first controlling postition to a second controlling position, means for operating said muting means at said first controlling position of said member, means for operating both said muting and said selecting means at said second controlling position of said member, and resilient means resisting movement of said member from said normal to said first controlling position and resisting movement of said member from said .first controlling position to said second controlling position with substantially greater force than from said normal position to said first controlling position.

9. In an automobile radio receiving System, a receiving set having a plurality of presettable means for presetting said set for selectively receiving a signal for any one of a plurality of transmitting stations, step-by-step selecting means for selecting a desired one of said presettable means, muting means for said set, a foot pedal having a normal position and movable from normal position through a first controlling position to a second controlling position, means for operating said muting means at said first controlling position of said pedal, means for operating both said muting means and said selecting means at said second controlling position of said pedal, resilient means resisting movement of said pedal from normal position, and means for abruptly increasing the resistance to movement of said pedal from said first controlling position to said second controlling position over the resistance to movement from said normal position to said first controlling position.

10. In a system for controlling a radio receiver, a plurality of presettable means for presetting said receiver for selectively receiving a signal from any one of a plurality of transmitting stations, selecting means for selecting a desired one of said presettable means, muting means for said receiver, and controlling means for said selecting means and muting means including an actuatable member having a normal position and movable from normal position through a first controlling position to a second controlling position, resilient means for resisting movement of said member from said normal position and returning the same to normal position, means for operating said muting means for muting said receiver upon a first movement of said member to said first controlling position, means for retaining said receiver in muted condition upon release of said member, means for releasing the muting of said receiver upon a subsequent movement of said member to said first controlling position and return to normal position and means for operating both said muting means and said selecting means upon movement of said member to said second controlling position and for releasing the muting of said receiver upon full release of said member from said second controlling position irrespective of the condition of said muting means prior to the movement of said member to said second controlling position.

11. In an automobile radio receiving system, a receiving set for receiving a signal from any one of a plurality of transmitting stations, muting means for muting said set, a foot pedal positioned at the floor board of said automobile for actuation by the driver of said automobile for operating said muting means to mute said sest, means for retaining the muting of said set upon release of said pedal after a first actuation thereof and means for releasing the muting of said set upon a subsequent actuation and release of said pedal.

12. An automobile radio receiving system comprising a receiving set having a plurality of presettable means for presetting said .set to receive a signal from any one of a plurality of transmitting stations, selecting means for selecting a desired one of said presettable means, and means for operating said selecting means to select any one of said presettable means including a foot pedal positioned at the floor board of said automobile to be actuated by the driver of said automobile, and means operated by said pedal for muting said set upon actuation of said pedal.

13. An automobile radio receiving system comprising a receiving set having a plurality of presettable means for receiving a signal from any one of a plurality of transmitting stations, stepby-step selecting means for selecting a desired one of said presettable means, and means for stepping said selecting means to select any one of said presettable means including a foot pedal p0- sitioned at the floor board of said automobile to be actuated by the driver of said automobile, and means for stepping said selecting means through a plurality of steps upon a single actuation of said pedal.

14. In an automobile radio receiving system, a receiving set having a plurality of presettable means for receiving a signal from any one of a plurality of transmitting stations, electrically operated step-by-step selecting means for selecting a desired one of said presettable means including a stepping mechanism, a foot switch positioned at the floor board of said automobile to be closed by the driver of said automobile, a circuit between said stepping mechanism and said switch and means for stepping said selecting means through a plurality of steps upon a single actuation of said pedal comprising a thermal element heated by current flowing through said switch for intermittently opening the circuit through said switch.

15. In an automobile receiving system, a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, a step-by-step rotary selecting device for selecting a desired one of said presettable means, and means for rotating said device in steps to select any one of said presettable means including a foot pedal positioned on the floor board of said automobile to be actuated by the driver of said automobile.

EUGENE F. MCDONALD, J11. 

